In August 2006, a pumice raft in the Tonga islands alerted sailors to the emergence of a new volcanic island known as Home Reef. After its appearance, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite tracked the new island’s progress. Although prominent in early October, the island had retreated somewhat by mid-November. Compared to the October image (inset), the image acquired on November 12, 2006, shows a smaller island with a different shape. Cloud cover overhead also obscures the November view.

For underwater volcanoes, erosion is not uncommon. The constant activity of the seawater eats away at the volcanic material. Volcanoes can grow in spurts of eruptive activity followed by periods of erosion that partially offset the growth.

NASA images created by Jesse Allen, Earth Observatory, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.